:root {
  --bg: #0f172a;
  --bg-card: #1e293b;
  --bg-card-2: #0b1424;
  --text: #e2e8f0;
  --text-dim: #94a3b8;
  --clock-ready: #4ade80;
  --clock-calibrating: #94a3b8;
  --clock-fallback: #fb923c;
  --clock-stale: #f87171;
  --warning: #fb923c;
  --warning-bg: rgba(251, 146, 60, 0.12);
  --error: #f87171;
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --primary-disabled: #1e3a8a;
  --border: rgba(148, 163, 184, 0.2);
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, "Roboto Mono",
    "Liberation Mono", "Courier New", monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC",
    "Microsoft JhengHei", Roboto, sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  min-height: 100vh;
}

body {
  display: flex;
  flex-direction: column;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 24px;
  border-bottom: 1px solid var(--border);
}

.brand {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.brand-sub {
  color: var(--text-dim);
  font-weight: 400;
  font-size: 14px;
}

.sound-toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--text-dim);
  font-size: 14px;
  cursor: pointer;
  user-select: none;
}

.sound-toggle input {
  accent-color: var(--primary);
  width: 16px;
  height: 16px;
}

.banner {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 24px;
  font-size: 14px;
}

/* [hidden] 要勝過 .banner 的 display: flex,否則 banner 永遠看得到 */
.banner[hidden] {
  display: none;
}

.banner-fallback {
  background: var(--warning-bg);
  color: var(--warning);
  border-bottom: 1px solid rgba(251, 146, 60, 0.3);
}

.content {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 32px;
  padding: 40px 24px 24px;
  max-width: 880px;
  margin: 0 auto;
  width: 100%;
}

.clock-section {
  text-align: center;
}

.primary-clock {
  font-family: var(--mono);
  font-size: 72px;
  font-weight: 600;
  line-height: 1.1;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.01em;
  color: var(--clock-ready);
  transition: color 0.4s ease;
}

.primary-clock.calibrating {
  color: var(--clock-calibrating);
  font-size: 28px;
  font-weight: 400;
}

.primary-clock.fallback {
  color: var(--clock-fallback);
}

.primary-clock.stale {
  color: var(--clock-stale);
}

.clock-meta {
  margin-top: 12px;
  color: var(--text-dim);
  font-size: 16px;
  display: flex;
  justify-content: center;
  gap: 8px;
  flex-wrap: wrap;
}

.dot {
  color: var(--border);
}

.sync-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 20px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px 24px;
}

.sync-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 14px;
}

.sync-label {
  color: var(--text-dim);
}

.sync-value {
  font-family: var(--mono);
  font-variant-numeric: tabular-nums;
}

.sync-value.warn {
  color: var(--warning);
}

.sync-value.error {
  color: var(--error);
}

.countdown-section {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  align-items: center;
}

.section-title {
  margin: 0;
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.06em;
  color: var(--text-dim);
  text-transform: uppercase;
}

.time-inputs {
  display: flex;
  align-items: center;
  gap: 6px;
  font-family: var(--mono);
  font-variant-numeric: tabular-nums;
}

.time-inputs input {
  width: 64px;
  padding: 8px 4px;
  background: var(--bg-card-2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  font: inherit;
  font-size: 18px;
  text-align: center;
  /* hide spinner */
  -moz-appearance: textfield;
  appearance: textfield;
}

.time-inputs input::-webkit-outer-spin-button,
.time-inputs input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.time-inputs input#inMS {
  width: 80px;
}

.time-inputs .colon {
  color: var(--text-dim);
  font-size: 18px;
}

.time-inputs input.invalid {
  border-color: var(--error);
}

.quick-buttons {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
}

.btn-quick {
  padding: 6px 12px;
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 13px;
  cursor: pointer;
  transition: background 0.15s ease;
}

.btn-quick:hover {
  background: rgba(148, 163, 184, 0.1);
}

.countdown-display {
  font-family: var(--mono);
  font-size: 60px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
  color: var(--text);
}

.countdown-display.idle {
  color: var(--text-dim);
  font-size: 36px;
  font-weight: 400;
}

.countdown-display.warning {
  color: #facc15;
}

.countdown-display.danger {
  color: var(--clock-stale);
}

.countdown-display.fired {
  color: var(--clock-ready);
  animation: fire-pulse 0.5s ease-out;
}

@keyframes fire-pulse {
  0% { transform: scale(1); }
  50% { transform: scale(1.15); }
  100% { transform: scale(1); }
}

.countdown-actions {
  display: flex;
  gap: 12px;
}

.btn-primary,
.btn-secondary {
  padding: 10px 20px;
  border-radius: 8px;
  font: inherit;
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease;
  border: 1px solid transparent;
}

.btn-primary {
  background: var(--primary);
  color: white;
}

.btn-primary:hover:not(:disabled) {
  background: var(--primary-hover);
}

.btn-primary:disabled {
  background: var(--primary-disabled);
  color: rgba(255, 255, 255, 0.5);
  cursor: not-allowed;
}

.btn-secondary {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}

.btn-secondary:hover {
  background: rgba(148, 163, 184, 0.1);
}

.footer {
  padding: 16px 24px;
  text-align: center;
  font-size: 12px;
  color: var(--text-dim);
  border-top: 1px solid var(--border);
}

.footer a {
  color: inherit;
  text-decoration: none;
}

.footer a:hover {
  color: var(--text);
}

/* === Responsive === */
@media (max-width: 1023px) {
  .primary-clock {
    font-size: 60px;
  }
  .countdown-display {
    font-size: 48px;
  }
}

@media (max-width: 639px) {
  .topbar {
    padding: 12px 16px;
  }
  .content {
    padding: 24px 16px 16px;
    gap: 24px;
  }
  .primary-clock {
    font-size: 44px;
  }
  .countdown-display {
    font-size: 40px;
  }
  .sync-card {
    grid-template-columns: 1fr;
  }
  .time-inputs input {
    width: 52px;
    font-size: 16px;
  }
  .time-inputs input#inMS {
    width: 60px;
  }
}